Noble-metal-free Ni–W–O derived catalysts for high-capacity hydrogen production from hydrazine monohydrate

Development of active and earth-abundant catalysts is pivotal to render hydrazine monohydrate (N2H4·H2O) viable as a hydrogen carrier. Herein, we report the synthesis of noble-metal-free Ni–W–O-derived catalysts using a hydrothermal method in combination with reductive annealing treatment. Interestingly, the thus-prepared Ni-based catalysts exhibit remarkably distinct catalytic properties toward N2H4·H2O decomposition depending upon the annealing temperature. From a systematic phase/microstructure/chemical state characterization and the first-principles calculations, we found that the variation of the apparent catalytic properties of these Ni-based catalysts should stem from the formation of different Ni–W alloys with distinct intrinsic activity, selectivity, and distribution state. The thereby chosen Ni–W alloy nanocomposite catalyst prepared under an optimized condition showed high activity, nearly 100% selectivity, and excellent stability toward N2H4·H2O decomposition for hydrogen production. Furthermore, this noble-metal-free catalyst enables rapid hydrogen production from commercially available N2H4·H2O solution with an intriguingly high hydrogen capacity of 6.28 wt % and a satisfactory dynamic response property. These results are inspiring and momentous for promoting the use of the N2H4·H2O-based H2 source systems.